One of the major concerns of manufacturers is the discovery of latent defects or flaws which may eventually lead to failure of a product, component or subcomponent. For this reason, manufacturers have employed various testing procedures that expose a mechanical product, component, or subcomponent to various stresses that would normally be expected to contribute to any number of possible failure modes. Once the failure modes were identified, the manufacturers could then redesign the products in order to reduce or even eliminate the failure modes. Some examples of stresses are pressure, ultraviolet radiation, chemical exposure, vibration, temperature (e.g., extreme heat or extreme cold, and rapid changes in temperature), humidity, mechanical cycling (e.g., repeatedly opening and closing a hinged door), and mechanical loading. It should be noted that the terms "product," "component," and "subcomponent," are being used interchangeably throughout the instant application.
Previously, laboratories typically conducted standard testing of mechanical products and components using traditional success based testing. This meant that the goal of the test was to measure the number of products or components that successfully survived a specified number of cycles with a specified stress source level (e.g., vibration, cycle load, temperature, humidity). This testing was generally based on field data and manufacturing/design experience.
Another testing approach was based on the introduction of all the stress sources at service levels to an entire system to provide the final verification test before production. This approach was intended to be a recreation of exact stresses seen on a system during field conditions. For example, an automobile cooling system would receive road vibration, glycol flow, pressure, heat, and ambient conditions just as would be expected to occur during a standard test track durability test.
Therefore, there is a need for a method and apparatus which is capable of generating all possible stress patterns in mechanical products and components under varying simultaneous stimuli in order to activate failure modes.
Testing in accordance with the present invention can lead to significant product quality improvements, design cost reductions, production cost reductions, reduced warranty repair expense, increased customer satisfaction, and increased market share.